1. Field of the Invention
The present invention relates to a machine for superfinishing annular workpieces such as bearings and particularly to a machine for superfinishing the inner race surface of annular workpieces.
2. Description of the Prior Art
There is a growing demand for higher accuracy of the inner race surface of annular articles, particularly bearings, and to meet this demand the bearing industry prepares two machines, a rough-finishing machine equipped with a rough honing stone and a fine-finishing machine equipped with a fine honing stone, so that upon completion of rough finishing of an annular workpiece by the rough honing stone, the workpiece is transferred for change of mounting. In this arrangement, however, two machines are required for finishing the inner race surface of annular workpieces and the change of mounting of workpieces results in deviation and misalignment, thereby degrading the finishing accuracy. Particulary in the case of finishing by the fine honing stone, an accuracy on the order of a 1/100000 mm is required, so that deviation and misalignment have a serious effect on finishing accuracy.
For superfinishing the outer surface of annular workpieces, the applicants have invented a superfinishing machine which alternatively applies any one of a plurality of honing stones to the outer surface, as is disclosed in applicant's copending U.S. patent application Ser. No. 416,707, filed Sept. 10, 1982 and now U.S. Pat. No. 4,485,592, dated Dec. 4, 1984. However, no such device is available for superfinishing the inner race surface of annular workpieces.